1Field of the Invention
This invention relates to treatment of obstructive portions of urinary passageways and is directed more particularly to a non-surgical method of treating obstructive strictures and segments of the urethra and ureter.
2. Description of Prior Art
It is known that obstruction of the urinary tract often is caused by the prostate gland enlarging, bearing against the urethra, reducing the urethral lumen and restricting urine flow. An enlarged prostate gland causes a number of symptoms urinary hesitancy or urgency, stranguria and post-void dribbling, as well as bladder stones and recurrent infections. Generally, patients suffering from such symptomatic prostatism may pursue one of the several treatments: undergo surgical prostatectomy, have inserted in the prostatic urethra an indwelling catheter, or receive intermittent treatment with a urethral catheter. In recent times, in some countries, a further alternative has been to have inserted in the prostatic urethra a coil stent.
Surgery subjects the patient to a number of hazards, such as post-operative bleeding, stricture formation at the urethra or bladder neck, incontinence, bladder spasm, urinary infection, reactive urethral swelling causing urinary obstruction, and epididymitis. Other risks include wound infection, retention of prostatic chips, retrograde ejaculation, bladder perforation, hyponatremia, intravascular hemolysis, and impotency. Furthermore, surgery requires about 1 to 2 hours in the operating room, plus an average of 3-5 days in the hospital (or more in complicated cases). About 10-15% of prostatectomy patients eventually require a repeat prostatectomy and probably 10% develop strictures with long-term costs.
Long term indwelling bladder catheterization to keep the urethra open carries a significant risk of infection. Frequent catheter changes may be made to prevent poor drainage due to blockage by encrustation.
Intermittent treatments by means of urethral catheter are normally performed by the patients themselves. Such self-treatment, involving moving a catheter through the urethra to the bladder, for many patients, particularly for the aged, is difficult or impossible.
A coil stent has been used experimentally in place of the indwelling catheter, with some success and several complications. The coil stent is also known as the spiral urethral prosthesis and as the Prostakath prostatic stent. The coil stent has a spring-like main body that remains in the prostatic urethra with a tapered end for easy insertion, a straight section which remains in the sphincter muscle area, and a distal coil which remains in the bulbar urethra to allow adjustment. While the coil stent re-establishes voiding in some patients, the stent causes a number of complications. The tapered end of the coil stent protrudes into the interior of the bladder, and may Cause discomfort and bladder irritability. The coil stent can migrate into the bladder, since only the enlarged prostate gland provides the force keeping the coil stent in place. The distal coil may perforate the bulbar urethra. Finally, the voiding rates have been only marginally improved.
It would, therefore, be beneficial to the medical arts to have available a method for treatment of obstructive prostatism which avoids surgery, the insertion of an indwelling catheter, and treatment, intermittent and permanent, with a urethral catheter, and their attendant problems. It would further be beneficial to have available a method for treatment of obstructive prostatism utilizing the placement of a stent in the prostatic portion of the urethra, but a stent having superior characteristics relative to the coil stent, and, in particular, a stent which may be easily positioned and repositioned. It would further be beneficial to have available a like method for treatment of obstructive segments and strictures of the ureter.